Zooming into the microbial and metabolic effects of citicoline use in kefir

Abstract This study focused on the metabolic and microbiological changes induced by citicoline in kefir. To demonstrate the microbial effects of citicoline in kefir, metabolite analysis was conducted using 16S rRNA and 28S rRNA metabarcoding. Additionally, kefir metabolite analysis was performed using gas chromatography–mass spectrometry (GC–MS). As a result of 16S rRNA analysis, the total bacterial abundances in the milk, kefir-citicoline (kefir-CT), and kefir samples were detected at rates of 82.83%, 79.23%, and 88.72%, respectively. The most dominant species in milk and kefir-CT samples were Halorubrum sp., accounting for 9.03% and 10.98%, respectively, whereas the most predominant species in kefir samples was Halostella sp. (9.5%). As a result of 28S rRNA analysis, the most dominant species in milk, kefir-CT, and kefir were Candida albicans (76.8%), (65.3%), and (67.68%), respectively. Furthermore, the GC–MS method was used to characterise the qualitative and quantitative changes of metabolites in milk, kefir, and kefir-CT samples and to determine the differences between the samples. As a result, a total of 25 different compounds were detected in these samples. Metabarcoding and GC–MS analyses have shown that citicoline use alters bacteria, yeast, and total volatile components. However, the addition of novel ingredients to foods with a wide range of health benefits, given their high diversity, creates opportunities for scientific research and diverse applications in the food market. Nevertheless, further research is needed in the future to understand the mechanisms within the body and in foods before these supplements can be added to foods or replace their natural variants.